When he gets a robocall, Robert B Eckhardt doesn’t necessarily hang up. If he isn’t too busy, Eckhardt, a professor of developmental genetics at Pennsylvania State University, stays on the line and asks random questions, such as, “Do your parents know what you’re doing?” If he can string the caller along for 10 minutes, Eckhardt considers it a minor victory in the war against telephone spam. Most people get annoyed by calls from telemarketers or scam artists. Some try to get even.